A carbon fiber composite material comprising carbon fibers and a thermoplastic resin is used to manufacture various molded articles and, various technologies, aiming high mechanical properties of a manufactured molded article and a good flowability at the time of the manufacture, have been proposed. For example, in JP-A-2011-178890, a composite material is proposed wherein the proportion, relative to the whole amount of fibers, of specified carbon fiber bundles in a carbon fiber composite material is suppressed, and the average number of fibers in the respective specified carbon fiber bundles is controlled in a specified range.
However, in such a carbon fiber composite material as described in JP-A-2011-178890 wherein the carbon fiber bundles in the carbon fiber composite material are thin, the proportion of the bundles is few and the carbon fibers are refined, although the mechanical properties of a molded article manufactured using the same are excellent, the flowability at the time of molding is low and moldability is poor. This is because the carbon fibers, which are reinforcing fibers, are sufficiently distributed, therefore stress is hard to be concentrated and the reinforcing effect due to the carbon fibers is sufficiently exhibited. On the other hand, the carbon fibers are crossed relative to each other to restrict their movements and, therefore, the carbon fibers become hard to be moved.
On the other hand, in JP-A-2011-178891, a composite material is proposed wherein the proportion of specified carbon fiber bundles in a carbon fiber composite material relative to the whole amount of fibers, similar to that described above, is set higher, and the average number of fibers in the respective specified carbon fiber bundles is controlled in another specified range. However, in such a carbon fiber composite material as described in JP-A-2011-178891 wherein the carbon fiber bundles are thick and the proportion of the bundles is many, although the flowability at the time of manufacturing a molded article using the same is high and the moldability is excellent, the adaptability at molding of carbon fibers for ribs and small-shape parts is poor, and the mechanical properties are low and the variations in the mechanical properties are great. This is because the adaptability of carbon fibers for small member parts is poor because the carbon fiber bundles are thick, stress is liable to be concentrated to end portions of the carbon fibers, but the carbon fibers are easily moved because the carbon fibers do not form networks.
Accordingly, it could be helpful to provide a carbon fiber composite material which can combine high flowability and mechanical properties, that have not been achieved by the conventional carbon fiber composite materials as those described above, and has few variations in mechanical properties, and which is excellent also in adaptability of carbon fibers for small parts such as ribs or the like.